Recently, the battery died over night. When I tried to jump it, got lots of sparks when connecting jumper cables. I was able to jump it, but then the radio was dead. All other electronics work. No bad fuses that I can find. Removed radio, the wire that supplies 12v at all times is dead. The switched 12v at radio connector is working. Don't have a schematic. Any thoughts? Something loaded the battery down overnight and jumping it burned open the load/short.